Battery Help
 

Hi. I am new to R/Cs and have a question about the batteries. What is the major difference between NICD and NIMH. I know one has a higher mAh then the other. And can I use either one on any motor and ESC or will it mess them up. Thanks. Justin

RE: Battery Help
 

NiMH has a higher charge density so you can get higer capacity cells for the same weight. They also don't self discharge as fast as nicads.

The older one's didn't have the current output capability of nicads but the newer ones are better.

NiMH also doesn't benefit from cycleing like NiCADs do.

http://www.rcbatteryclinic.com

RE: Battery Help
 

Another good source for battery onfo is www.powerstream.com/BatteryFAQ.html
I also think you will find all manufacturers admit that NiMh has a HIGHER self discharge rate than NiCads do. Each type of battery has its own advantages and dissadvantages. The most robust and dependable is still the NiCad for airborne use, especially if long life, ability to survive abuse and number of charge/discharge cycles are important.

RE: Battery Help
 

The Ni-MH that are available to us today may be treated essentially the same as Ni-Cds –EXCEPT FOR PEAK CHARGING. You have to be careful here. Some chargers will accommodate them, others won’t - and end up severely overcharging them to the point of destruction.

In a given cell size Ni-MH has on the order of 20 to 30% more capacity than Ni-Cds. They have slightly higher internal resistance, but not enough to concern us in most R/C control applications. This higher internal resistance can be of concern in electric flight operations where it is common practice to add an additional cell to compensate. They have a shorter cycle life in general, but again not enough to be of real concern. Most people run out of calendar life before cycle life in flying R/C. Meaning that the separator system in the battery (same for both types) fails (shorts) before the cells fade away in capacity delivery ability. Ni-MH are less tolerant to abuse (excessive high rate discharge, excessive overcharge, vibration, cell reversal) than Ni-Cd – but again, it seldom becomes an issue if reasonable care is given in the installation and maintenance of the packs. Ni-MH capacity falls off with cycling whereas Ni-Cd stays pretty constant, seldom going below 80% before shorts develop. Ni-MH has a higher self-discharge rate (3-4%/day) than Ni-Cd (1%/day). Ni-MH cost a bit more per Ah of capacity.

Ni-Cd and Ni-Mh made in China may still be a crap shoot, somr days OK and others pure crap. It is hard to copy process control.